Nick, That chart uses 2000 census data. I'm sure that in 2000, before the light rail was built, it was negligible. Things have probably changed a little since then. As for the dense cities, ridership has been increasing here in Washington and in places like New York and San Francisco and other transit heavy places so I'm sure the chart will look even better after the next census.

duncan: It's a common claim by anti-PT types that in fact most trips in NYC are by car. I presume they are talking about the greater NYC district (which includes boston and washington perhaps?). What is your take on this?

No, greater NYC is greater NYC, not Boston or Washington. Suburb-to-suburb commutes are almost exclusively by car, since the transit system froze before any suburbs developed as job centers.

Basically, commutes from within NYC, Long Island, or Westchester into Manhattan are almost exclusively by transit (80% for the suburbs, almost 90% for NYC); commutes within NYC that don't go into Manhattan, and commutes from New Jersey to Manhattan, are split about fifty-fifty; all other commutes are mostly by car.

And of course the many daily non-commute trips that people make are done by walking in Manhattan and to a somewhat lesser degree in most of the rest of NYC as well, but by car in the suburbs and to some extent the outer boroughs. Except I bet the car trips get counted, but my walking to the supermarket does not. Especially if I just stop by on the way home from the subway.